1. Field of the Invention
This invention relates to a system and method for handling and storage of marine cargo containers providing higher throughput rates than has been possible in the past, and permitting quick retrieval of stored containers for delivery to a marine vessel or a land carrier, thereby minimizing delays and unnecessary use of dock and cargo loading space associated with prior art methods of storing and handling marine containers.
2. Discussion of the Prior Art
Marine containers for shipment of cargo are generally rectangular structural containers that are provided with ISO fittings at each of their upper and lower corners. Marine containers are of various lengths, typically 20, 24, 30, 40, or 45 feet. These different lengths of containers are normalized when evaluating marine cargo container storage to a twenty foot equivalent unit ("TEU"). The conventional methods and equipment for handling and storage of marine containers use overhead cranes having a spreader with hooks, which hooks fit into and engage openings in the ISO fittings at the upper corners of the container. Thus, for example, in handling inbound marine containers, a dock crane will lift such containers from the deck or hold of a marine vessel and deliver them to a truck. The truck will then transport the container to a storage area, where it is carried by a transtainer (a rail guided or rubber tired overhead straddle crane), and stacked on top of other such containers. Containers stacks commonly contain as many as six such containers, all stacked one on top of the other. Such stacking is possible because the containers are structural elements, and they are typically stacked such that the ISO fittings of an upper container are seated on and supported by the ISO fittings of the container beneath it.
The stored container will then be retrieved from storage when the overland carrier, such as a truck or railway car, arrives and is ready to receive the container. The retrieved container is re-hooked to the transtainer, and then lifted and carried by the transtainer to a truck loading site, where it is then mounted to a truck bed.
It is to be appreciated that in order to retrieve a selected container, that it may be necessary to move some five other containers in order to obtain access to the desired container, i.e., when the desired container is at the bottom of a stack of six containers. This shuffling of containers is time inefficient and creates additional problems in tracking the location of the containers that were moved; alternatively, it is then necessary to replace the five containers into their original stack location so that they remain in their original assigned location.
The same procedures will generally apply when containers are moving in the reverse direction, i.e., when containers are being delivered to a marine terminal by ground transportation, for storage and subsequent loading on a marine vessel for overseas transport. Thus the container will be picked up from the bed of the truck, stored in the storage area, and then retrieved for loading to a marine vessel.
It has been proposed to automate the storage of marine containers, however, to date, no such system has provided an integrated system and method for handling and storage of marine containers to provide completely automated handling of the containers. Moreover, no such automated system has provided an apparatus and method providing random or near random access to the marine containers in the storage area, so that the containers can be rapidly retrieved on demand.
In the field of air cargo handling systems, which involves the handling of air cargo containers, which have a thin aluminum base lacking structural support, several cargo bin handling systems using a random access storage system have been proposed and successfully implemented.
It has also been known in general in connection with warehousing of goods at their location of manufacture, to store pallets of warehoused materials in open frameworks allowing near random access to the stored pallets, for example, as disclosed in U.S. Pat. Nos. 4,273,494 and 3,417,879. However, heretofore, these types of systems have not been used or proposed in connection with marine container storage, due to the unique difficulties of handling such containers.